The present invention relates to a time adjusting means for an electronic timepiece having both a hand displaying type device and an optically displaying device.
In the prior art, there are two methods generally used for adjusting the time of an electronic timpiece having a hand displaying device and an optically displaying device. One method is a method in which the adjusting operations for the hand displaying device and the optically displaying device are independently carried out, and the other method is a method in which the adjusting operations are carried out in synchronization for units of a second below a unit of a minute. For example, there is a time-adjusting method in which 30 seconds and over is counted as a minute and 29 seconds or less is ignored and not counted in the optically displaying device, and the same operation that 30 seconds and over is counted as a minute and 29 seconds or less is ignored and not counted, is also carried out in the hand displaying device by a quick feeding of forward or reverse drive pulses to a stepping motor in synchronization with the adjusting operation of the optically displaying device. This method will be referred to as "a second linking" time-adjusting method, and on the other hand, the method of the present invention will be referred to as "a below second linking" time-adjusting method. Also, there is another method wherein a counter for counting time units below a second (fractions of a second) is reset when a correction for the second in the hand displaying device and the optically displaying device is carried out.
If the timepiece is of the type in which the hand displaying device is operated independently of the operation of the optically displaying device, no specific interconnecting arrangement is required, and the arrangement can be simple so that in this regard it is advantageous that the hand displaying device can be adjusted independently of the adjustment of the optically displaying device. However, in such timepieces the movement of the second hand of the hand displaying device is not necessarily coincident with the time indicated by the figures displayed by the optical displaying device and this is a serious drawback.
In addition, in the case of a timepiece having an alarm function which is performed in the optically displaying mode, the driving of the alarm buzzer is often carried out at the same time as the driving of a motor. Therefore, it is disadvantageous if the motor does not move because the battery voltage is lowered due to an increase of the internal resistance of the battery under low temperature conditions.
Although the value of the timepiece is improved when the time indicated by the second hand is coincident with the time indicated by the figures of the seconds digit when the second linking is employed, a device for detecting the position of the second hand or a particular operation for obtaining the coincidence between the indications of the second hand and the seconds digit at the initial setting time is required so that a relatively complex operation is required.
Of course, it is impossible to use these two timepieces as completely separate timepieces in the display of seconds.
The time delay of one second may be produced at a maximum depending upon the reset timing, when the counter for counting the time not more than one second is merely reset. For example, when 30/60 seconds and over is counted as a second and 29/60 seconds or less is not counted and dropped in the optically displaying device, if the counting result in the digit of the 10.sup.-1 seconds is 0.9 seconds, it follows that the second hand moves after 1.9 seconds have elapsed since the previous movement.